The club paid a £10 million fee to release Frank from his contract with Brentford, which still had two years left to run.
Thomas Frank previously managed Brentford from October 2018, guiding the team into the Premier League through the Championship playoffs in 2021.
During his time at Brentford, Frank helped the team establish themselves in the top flight despite having a relatively modest budget.
Under Frank's leadership, Brentford finished the previous season in 10th place in the Premier League. He will now take over a Tottenham team that finished 17th in the domestic league.
Tottenham's poor domestic performance led the chairman, Daniel Levy, to decide to let go of Postecoglou, even though he achieved success in the Europa League.
Postecoglou led the team to victory in the Europa League, securing their first piece of silverware in 17 years, but was let go just 16 days later.
Frank's experience and achievements with Brentford have led to his appointment as Tottenham's new head coach, and he will aim to improve the team's performance in the domestic league.
Tottenham is looking forward to working with Frank and believes he has the skills and expertise to lead the team to success.